Straddled Vehicle Cross Frame Centroid Positioning
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Solution Overview
Problem
Existing motorcycles face challenges in minimizing the transmission of pitching energy from the road surface to the rider and maximizing tire-road contact time on bad roads, due to limitations in the positioning of the cross frame and rear cushion unit, which affect ground clearance and shock absorption.
Innovation Solution
A straddled vehicle design with a cross frame centroid positioned within a specific area defined by extensions of the connecting and main frames, allowing the rear cushion unit to maintain a high position and absorb upward forces directly, while the main frames can bend to absorb shocks, thereby reducing pitching energy transmission and increasing tire-road contact time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the cross frame is placed at a low position, then the upper end portion of the rear cushion unit is positioned low, but the ground clearance is reduced and the rear cushion unit cannot effectively absorb upward forces
Solution Approach 1:
The patent changes the positional parameter of the cross frame from a low position to a high position (specifically, the centroid of the cross frame is positioned within a predetermined area that is higher than the connecting frames). This parameter change allows the upper end portion of the rear cushion unit to be positioned high, enabling it to effectively absorb upward forces from the road surface while maintaining adequate ground clearance.
2Shape
If the cross frame is placed at a high position, then the distance between the head pipe and cross frame is short, but the main frame cannot bend to absorb shocks
Solution Approach 1:
The patent positions the centroid of the cross frame within a predetermined area that balances two requirements: being high enough to allow effective shock absorption by the rear cushion unit, and being far enough from the head pipe to allow the main frame to bend and absorb shocks. This optimized parameter placement resolves the contradiction between compact distance and shock absorption capability.
3Shape
If the rear cushion unit is installed in an inclined attitude to ensure ground clearance, then the ground clearance is maintained, but the upward force from the road surface is not absorbed directly
Solution Approach 1:
The patent positions the upper end portion of the rear cushion unit at a high position (with the centroid of the cross frame within a predetermined area), creating an equipotential condition where the rear cushion unit can maintain a substantially vertical attitude. This eliminates the need for inclined installation, allowing the unit to directly absorb upward forces from the road surface while maintaining adequate ground clearance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces the transmission of pitching energy from the road to the rider and increases the time the tires are in contact with the road surface, enhancing comfort and stability on bad roads.
Implementation Method 1
the rear cushion unit needs to be installed in an attitude that is substantially inclined from the vertical line or the stroke of the rear cushion unit needs to be limited, in order to ensure the minimum ground clearance. As a result, the upward force that is received from the road surface by the rear wheel is unlikely to be absorbed directly by the rear cushion unit.
Implementation Method 2
when a shock is applied onto the head pipe 101 from the front, the main frame 102 is unlikely to be bent left and right. Thus, a shock absorbing effect from the bending of the main frame 102 is unlikely to be realized.
Data Source
AI summary
A straddled vehicle includes a cross frame connected to a left main frame and a right main frame. As the vehicle is seen from the side, a centroid of a central cross section in a vehicle width direction of the cross frame is located within an area that is delimited by an upper extension obtained by extending rearward an upper outline of the left connecting frame, a lower extension obtained by extending rearward a lower outline of the left connecting frame, an upper outline of the left main frame and a lower outline of the left main frame.